Electrochemical concentration of liquids.



No. 896,749. PATENTED AUG. 25, 1908. G. W. NISTLE & R. L. GIFFORD.

ELECTROCHEMICAL CONCENTRATION OF LIQUIDS.

APPLICATION FILED JUNE 22, 1907.

UNITED STATES PATENT OFFICE.

\ GEORGE W. NISTLE, OF NORTH MUSKEGON, MICHIGAN, AND ROBERT L. GIFFORD, OF

CHICAGO, ILLINOIS.

Specification of Letters Patent.

Patented Aug. 25, 1908.

Applicatidn filed June 22, 1907. Serial No. 380,245.

To all whom it may concern:

Be it known that we, GEORGE W. NISTLE and ROBERT -L. GIFFORD, citizens of the United States, residing, respectively, at North Muskegon, in the county of Muskegon and State of Michigan, and Chicago, in the county of Cook and State of Illinois, have invented a certain new and Improved Process in the Electrochemical Concentration of Liquids, of which the following is a specification.

This invention relates to an improved process for the electro chemical concentration of liquids, and relates more s ecifically to a process whereby the heat an chemical reaction incident to electrolysis is availed of to effect, or aid in eflecting, the concentration of liquids of that character capable of acting as electrolytes.

Among the objects of the invention are to expedite the concentration of liquids; to facilitate the recovery of the maximum amount of a desired chemical in waste liquids of the character contemplated; to provide a process which expedites the conversion of the iquid into that condition which is favorable for crystallization of the contained chemical, following the concentrating part of the rocess; to provide a process which avoi s repeated handling or transferring of the material, and in general to provide an improved process of the character referred to.

To the above ends the invention consists in the matters hereinafter described, and more particularly pointed out in the appended claims.

In the manufacturing art it is common to cleanse iron parts by placing them in an acid pickle for a desired length of time, and after such pickle has been Used for 'a certain period its free acid is largely eliminated and the bath must be renewed. The partially exhausted pickle liquor is frequently thrown away, but it is sometimes concentrated and the free acid satisfied by supplying its aflinity for iron in order that the chemical may be precipitated as a salt of iron.

As a specific example, it is customary to pickle sheet iron in a solution of sulfuric acid preparatory to using the iron for making enameled ware, and after the acid solution has become so weakened that the pickling process becomes uneconomical because of the length of time required to clean the iron, the liquid is sometimes concentrated by applying heat and evaporating it, and at the same time scrap iron or filings are placed in the solution in order that the free acld may be fully satisfied. Thereafter, when the solution has been concentrated to the proper degree, the solution is cooled, whereupon the sulfate of iron crystallizes out this being the by-product to be recovered in this instance.

We have discovered that galvanic action or electrolysis may be brought into use and used as an auxiliary in the concentration of such liquids with a marked shortening of the time required for concentration and a substantial increase in economy.

Describing the process in general terms, we place the liquid to be concentrated in any suitable receptacle within which is arranged a heating coil or the like which should, of course, be made of such metal as .to be unaffected or substantially unafiected by the solution. Through this heating coil or the like is circulated a heat medium, such as steam or warm water, and within the solution and exposed to the action thereof is placed iron (usually scrap iron) to supply the aflinity of the acid therefor. Now, inasmuch as we have the elements necessary to form a galvanic couple, in that the iron is attacked chemically by the acid, the acid is an electrolyte and the heating coil may be used as the negative, we electrically connect the mass of iron with the heating coil and avail of the alvanic action which ensues as a means 0 hastening the process.

Describing the method more specifically, and as carried out by the a paratus shown in the drawing, which is wel suited for that pur ose, 1 designates as a whole a suitable tan which is desirably open at its top and is ada ted to contain a desired quantity of the aci solution. 1 1 1 h h 2 designates a supp y pi e t HOUO i w ic the acid solution may be discharged into the tank.

3, 3 and 3" designate a series of test cocks arranged at various levels, and 4 designates a main eduction pi e leading from the bottom of the tank an controlled by a valve or turn-cock 5.

6 designates as a whole the heating coilwhich, as shown, consists of a series of ops 7, each of which communicates at one end with a supply header 8, and at its op osite end with a return header 9. With eac end of the su ply header communicates a pipe, as 10 an 11; these pipes being respectlvely controlled by valves 12 and 13, and one pipe beinglarranged to communicate with a source of eating fluid and the other with a source of cooling fluid. The return header 9 is provided with an eduction pipe or outlet 14. In practice it is desirable that the series of heating and cooling loops 7 be distributed across the lower part of the tank in the manner shown," and inasmuch as said loopsall connect with the common header 9, they are obviously electrically in metallic connection with the latter.

Within the tank, above and free from the loops 7, is sup orted a frame, which desirably takes the orm of a crate or basket 15 of wood or other suitable insulating material made of open work construction so as to afford a free circulation of the acid electrolytic solution therethrough. Conveniently this crate is supported from overhead so that it may be raised out and lowered into the tank at will. Within the crate or basket is supported a mass of iron, preferably scrap iron, and in metallic connection with this mass of iron is an electric conductor 16. Preferably the conductor 16 is provided with a plurality of branch wires which are spread across the bottom of the crate before the mass of iron is placed therein so as to insure good metallic contact with the mass, and by arranging the wires in the bottom of the crate, the iron as it is consumed and settles down maintains good electrical contact with the conductors throughout the operation.

The conductor or conductors 16, and the heating and cooling pi es are made of brass, copper, or other meta not affected or substantially affected chemically orelectro chemically. -The conductor 16 is electrically connected with the heating and cooling system,

at a point outside of the solution by means of a conductor 17, and in order that the external circuit thus formed may be opened and closed at will a switch 18 is interposed between the conductors 16 and 17.

When the electrolyte becomes extremely weak, 1 e., the free acid has nearly all been eliminated, the electrolytic action may be augmented or kept up by supplying electric current from an external generator, and to this end the switch 18 is adapted to close a circuit between the conductor 16 and a contact 19 which forms one terminal of a conductor 20 leading to any suitable generator 21. This opens the circuit between conductors 16 and 17 The other side of thegenerator is connected through a conductor 22 with the conductor 17 so that by simply changing the position of the switch 18 the generator circuit is included in the battery circuit. v

The method of carrying out our improved process with the aid of th1s apparatus will be obvious, but may be briefly stated. A suitable quantity of the acid solution having been placed in the tank, the basket or crate with its charge of scrap iron and with the conductor wires 16 properly connected with the iron is lowered into the tank and the connection made between the conductor 16 and the switch contact 18 in case it is not desired to connect the generator in circuit. The switch being in" the position shown in the drawing, electrolytic action immediately ensues. At the same time a heating fluid, as for example steam, is introduced through one of the pipes, say pipe 10, and circulating through the series of loops the water of condensation passes out through the return header 9. Evaporation of the acid solution ensues, this evaporation being effected by the combining heat introduced through the heating system and that produced by electro chemical action, and furthermore the decomposition of the liquid by electrolysis gasifies substantial quantities thereof, and this gas in turn carries off with it vapor, so that the evaporation due to the conjoint connection of steam and electrolysis is comparatively rapid.

It is to ing some liquids, notably sulfuric acid solutions, the temperature must not be allowed to rise too high, because if the temperature exceeds a certainrpoint (which is substantially below that at which steam is gener ated at ordinary atmospheric pressure) a chemical reaction is set up which results in producing a salt different from that wanted, which is sulfate of iron of the formula FeSO,. The necessity of maintaining such comparatively low temperature obviously renders the evaporation and concentration of the li uid extremely low, unless expedited by the e ectrolytic action described, and it is this relatively slow process which has made the recovery of the by-product a matter of doubt ful economy in the past.

After the liquid has been sufficiently concentrated and its affinity for iron substantially or a proximately satisfied, we then shut off the circulation of heating fluid through the loop system and introduce instead a cooling fluid,, and thereby rapidly lower the temperature of the solution in the tank to that stage at which crystallization will be best brought about. The liquid is then transferred to the crystallizing tank 23 and the salt allowed to crystallize out.

As an intermediate subsidiary step which may or may not be employed, after the electrolytic action has begun'to subside as the affinity of the acid for iron approaches saturation, we change the position of the switch 18 so as to open the short circuit between the conductors 16 and 17 and include the generator circuit, whereupon the generator is operated and sends an auxiliary current to the battery. This reinforces the galvanic ac-- be particularly noted that in treatof the current supplied by the generator I tion a heating coil, connectin the iron elecwould be the same as that generated by the galvanic battery itself. In this connection it is to be observed that inasmuch as the mass of iron constitutes the positive and the loops of the heating system the negative of the galvanic couple there will be no tendency on thepart of the electrolyte to attack the metal of. the heating and cooling s stem.

While we have given one speci '0 example of a practical application of our process, we do not wish to be understood that the proc ess is limited to the recovery of this byproduct. On the contrary, the method may be employed for promoting the concentra-- tion of other acids where the conditions are such that a galvanic couple may be formed.

We claim as our invention:

1. The improvement in the art of concentrating electrolytic liquids of acid character which consists in combining with the acid a metal for which the acid has chemical affinity to act as an anode and another electrode which will form a negative electrode, electrically connecting said electrodes and thus effecting electro chemical action and supplying heat to said liquid to cooperate with the electro chemical action in concentrating the liquid.

2. The improvement in the art of concentrating acid solutions having a chemical afiinity for iron which consists in placing in, or subjecting to the action of, the acid the mass ofiron, arranging in orin contact with the acid a cathode electrode electrically connecting said cathode electrode with the mass of iron eXteriorly of or out of contact with the acid and thus causing electro chemical action and concurrently supplying auxiliary heat to said liquid from an external source.

3. The improvement in the. art of concentrating acid solutions which consists in plac-' ing in, or subjecting to the action of, the acid a mass of iron, submerging in the acid solucathode e trically with said heating coi to 'form with the acidsolution, the mass of iron and the heating coil a galvanic battery and concurrently with the electro chemical action circulating heating fluid through said heating coil.

4. The improvement in the art of concentrating electrolytic liquids, which consists in combinin with the liquid suitable anode and laments to form with the liquid a galvanic couple, electrically connecting said elements and effecting electrolytic action, concurrently heating the liquid from an external source, continuing the combined electro chemical action and heating until the electrolytic action substantially subsides then passing electric current into and throughv the battery so formed and in the same cur rent direction until the desired degree of concentration has been efiected.

5. The improvement in the art of concentrating acid solutions, which consists in combining with the acid a mass of iron and a cathode electrode and connecting the iron and cathode to form a galvanic battery continuing the action of said battery and concurrently supplying heat to the liquid from an external source and augmenting the electrolytic action of said battery by passing electric current from an outside source through the battery in its normal flow direction.

GEO. W. NISTLE. ROBERT L. GIFFORD.

Witnesses to signature of George W. Nistle:

W. O. NIsTLE,

SARAH M. PLACE.

Witnesses to signature of Robert L. Gifford:

ALBERT H. GRAVES, I EMILIE Ross. 

